Thank you for the ideas. So far, this is what I've come up with.
Create part templates for the different stocks of plywood we use (e.g. 3/4", 1/2" etc). With the Stocksize variable set to equal length and width of the sketch of the part. Length and width are set at driven dimensions...
I'm trying to get the BOM on a drawing sheet to automatically show the length, width and depth of a part. Or put another way, give the custom properties of thickness and/or stock size real values.
I typically design parts in the assembly view and often and don't define a lot of dimensions...